1. Field of the Invention
The present invention relates to a motor vehicle friction clutch with automatic wear adjustment. The clutch comprises a flywheel which rotates about a rotational axis, a clutch housing which is fixed to the flywheel to turn with the flywheel, a pressure plate that is non-rotationally connected to the clutch housing and which pressure plate can be axially displaced in relation to the flywheel and a clutch disc that is rotationally arranged between the pressure plate and the flywheel. Friction linings are disposed around the rotational axis in relation to the flywheel with a membrane spring element installed to pre-stress or pre-tension the pressure plate in the direction of the flywheel. The membrane spring element acts on the pressure plate in a radial outer area through a wear adjustment device and the membrane spring element is supported in a radial center area at the clutch housing. The clutch can have at least one clearance sensor which is arranged at the pressure plate, and the clutch has a control lever segment that acts with the wear adjustment device. The clutch can also have an axial stop segment which acts with the flywheel to adjust for wear, whereby the clearance sensor can be displaced axially in relation to the pressure plate. At least one spring element can hold the clearance sensor to the pressure plate by means of a friction ratchet to axially fix or position the clearance sensor in relation to the pressure plate.
2. Background Information
A known motor vehicle friction clutch with the construction described above is shown in DE-A-43 06 688. This publication discloses a motor vehicle friction clutch where an axially extending connecting hole or boring is provided in a radial outer periphery of the pressure plate. This connecting hole is axially penetrated by a pin. The pin forms the axial stop segment for the clearance sensor. To axially set the clearance sensor with respect to the pressure plate, the outer diameter of the pin and the inner diameter of the hole in the pressure plate are adjusted in such a manner that even a slight tilting or angling of the pin in relation to the pressure plate will cause a friction press-fit or friction ratchet or connection of the pin to the pressure plate. In other words, the angling of the pin with respect to the hole will cause the pin to be biased against the side of the hole. To create this moment of tilt, a coil pressure spring that acts between the pressure plate and the free end segment of the pin is provided, whereby the longitudinal axis of the spring is tilted in relation to the longitudinal axis of the pin and the center axis of the connecting hole. This spring thus tilts the pin in relation to the center axis of the hole and thereby causes the friction ratchet or biasing.
For the clearance sensor to function correctly in this known motor vehicle friction clutch, the connecting hole in the pressure plate must be highly precise with respect to its diameter and its positioning on the pressure plate. In assembling the clearance sensor, the coil pressure spring must first be slid or positioned over a pin which is separate from the control lever segment of the clearance sensor. The pin is then guided through the connecting hole and into the pressure plate. The end segment of the pin, which was guided through the connecting hole, can then be connected with the control lever segment. This work process is rather complicated because the clearance sensor must be assembled directly on the pressure plate.
DE-A-44 12 107 shows a known motor vehicle friction clutch where the moment of tilt is not provided by a coil pressure spring acting between the pin and the pressure plate. Instead, it provides a coil tension spring which creates tensible force between the pressure plate and a radial outer end segment of the control lever segment of the clearance sensor and thus achieves to the desired moment of tilt. Here again, the pin is fixed in a connecting hole in the pressure plate by friction ratchet in the axial direction. The assembly of this motor vehicle friction clutch, and particularly the clearance sensor, is subject to the same problems as previously described.